The present invention relates to a machine and method for configuring the winding head of a stator for a rotary electrical machine.
More particularly, the invention relates to a machine for configuring the winding head of a stator for a rotary electrical machine, of the type in which the stator includes an annular cylindrical body having a set of open axial slots, of the type in which conductors, generally U-shaped and of rectangular cross section, are inserted into the axial slots in such a way that their free end portions extend substantially axially upwards on the side of the upper transverse face of the body, so as to constitute the winding head, of the type in which each axial slot contains at least two axial branches of the conductor, which are superimposed radially so as to define two layers of conductors, of the type comprising a support body which immobilises the stator body and conductors, together with concentric sleeves, each of which is of substantially tubular form, and which are arranged coaxially with the stator body, each sleeve being mounted for rotation about its axis with respect to the support body, wherein each sleeve includes, in facing relationship with a respective one of the said layers of conductors of the winding head, a lower axial end or working or configuring part, which is formed with gripping means for gripping the free end portions of the conductors in a respective one of the said layers, and of the type in which driving means are arranged to rotate each said sleeve in a direction of rotation opposite to the direction of rotation of an adjacent one of the said sleeves, whereby to bend in opposite directions the free end portions of the conductors in two adjacent said layers.
Machines of the above kind are already known for configuring the winding head of an alternator stator. Such a machine generally includes tubular sleeves, the axial working or configuring end part of which is crenellated in such a way as to define gripping slots, with each gripping slot having a rectangular profile in circumferential and axial cross section. Each gripping slot has a form complementary with the free end of each axial branch of one of the said conductors, in such a way that it can receive and hold the latter. When a said sleeve is rotated about its axis and displaced axially towards the winding head, the free end portions of the associated axial branches are bent at the exit of the axial slots in the stator body, in the direction of the rotational movement.
It is noted that the free end portions which are received in the gripping slots keep their substantially axial orientation because they are immobilised by the free ends which are held in the gripping slots. Consequently, each free end portion is bent twice, namely once in the vicinity of the exit or open side of the axial slot, and once in the vicinity of the free end, before entry to a gripping slot.
This type of tooling is not well suited to the configuring of a winding head which has more than two free end portions superimposed radially in each axial slot of the stator body. In addition, this kind of tooling does not enable a winding head to be formed in which the free end portions are bent only once in the mouth of an axial slot in the stator body.
An object of the invention is to overcome the above mentioned drawbacks. With this in view, according to the invention, a machine for configuring the winding head of a stator for a rotary electrical machine, of the type in which the stator includes an annular cylindrical body having a set of open axial slots, of the type in which conductors, generally U-shaped and of rectangular cross section, are inserted into the axial slots in such a way that their free end portions extend substantially axially upwards on the side of the upper transverse face of the body, so as to constitute the winding head, of the type in which each axial slot contains at least two axial branches of the conductor, which are superimposed radially so as to define two layers of conductors, of the type comprising a support body which immobilises the stator body and conductors, together with concentric sleeves, each of which is of substantially tubular form, and which are arranged coaxially with the stator body, each sleeve being mounted for rotation about its axis with respect to the support body, wherein each sleeve includes, in facing relationship with a respective one of the said layers of conductors of the winding head, a lower axial end or working or configuring part, which is formed with gripping means for gripping the free end portions of the conductors in a respective one of the said layers, and of the type in which driving means are arranged to rotate each said sleeve in a direction of rotation opposite to the direction of rotation of an adjacent one of the said sleeves, whereby to bend in opposite directions the free end portions of the conductors in two adjacent said layers, is characterised in that the gripping means of each said sleeve consist of a set of gripping slots, each of which has a substantially right-angled profile in circumferential and axial cross section, and each of which receives the free end portion of a respective conductor, whereby the said rotation of a said sleeve produces a single bending action at the exit of the axial slot for each conductor in the associated said layer.
According to a preferred feature of the invention, the configuring machine includes means for controlling the axial displacement of each said sleeve with respect to the support body, whereby to combine downward axial straight line motion with the rotary motion, so that the contact surface between the free end portion of each conductor and the associated gripping slot are optimised.
According to another preferred feature of the invention, each said conductor has a width greater than or equal to its thickness, and the conductors are superimposed radially in each axial slot in the direction of the thickness.
According to a further preferred feature of the invention, each said sleeve is caused to move in rotation until each free end portion describes at the exit of the axial slot an angle of about 45xc2x0 with respect to the annular upper transverse face of the stator body.
According to yet another preferred feature of the invention, at the end of the rotational movement of the said sleeves, the sleeves are given a downward axial straight line movement with respect to the support body whereby to level up the height of the free end portions of the bent conductors.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of preferred embodiments of the invention, given by way of non-limiting example only and with reference to the accompanying drawings.